This application relates to improvements in rod guides or the like for rotating sucker rods and pumping oil wells and more particularly to rod guides having reduced drag resistance, turbulence and energy demand.
As is well known, sucker rods in pumping oil wells normally extend longitudinally through the well bore or tubing and are reciprocated or rotated therein during the pumping operation. Since most well bores are not straight, and many are purposely drilled at an angle, the rods frequently wear against or engage the walls of the tubing during reciprocation or rotation thereof, which creates detrimental wear on the rods, rod couplings and tubing.
One usual apparatus for pumping well fluids includes a pump connected to the lower end of the tubing which is reciprocated the string of sucker rods. The sucker rods, or rod string, are connected to a reciprocating mechanical lift for alternately pulling the string upward and then allowing the string to move downwardly by gravity.
An alternative apparatus for pumping well fluids includes a progressing cavity pump connected to the lower end of the tubing. A rotor is rotated within a stator of the pump by the string of sucker rods. The sucker rods, or rod string, are connected to a mechanical drive for rotating the string to raise the well fluids.
Since the rotation of the rod string provides the force necessary to move well fluids upwardly through the tubing, if the resistance to rotational movement of the string is excessive, energy is unnecessarily expended. Further, if the rotation of the rods induces large amounts of pressure drop, turbulence or resistance to flow at a point, this localized turbulence can promote excessive wear of the rod and tubing or even induce fracture.
Heretofore, conventional rod guides of the paddle type have been used to avoid unnecessary wear of the rod against the tubing. However, these paddle type rod guides induce excessive resistance to fluid flow and cause greater turbulence and considerable tubing wear where it is mounted on the rotating rod.
In order to avoid this problem, occasionally substantially solid rod guides are employed with progressing cavity pumps in wells. To reduce restriction of fluid flow, the solid guide must leave substantial clearance between the guide and the tubing wall which permits only a reduced erodible volume of material to protect the rod coupling.